Surface anisotropy induced spin wave nonreciprocity in epitaxial La0.33 Sr0.67 MnO3 film on SrTiO3 substrate

Spin wave propagation in perovskite La0.33 Sr0.67 MnO3 films epitaxially grown on a SrTiO3 substrate of (001) orientation was investigated using an all electrical spin wave spectroscopy technique. The spin wave nonreciprocity in amplitude, resonance frequency, and group velocity of the transmission spectra were observed. The origin of the spin-wave nonreciprocity is attributed to the out-of-plane surface anisotropy, with a value of 1.3 mJ/m2 at the interface with the substrate, as extracted from the theoretical model. The magnetic field dependence of the frequency shift is attributed to the perpendicular surface anisotropy. The important role of the surface anisotropy in the spin wave nonreciprocity was further confirmed by the angle dependent measurements of the spin wave transmission spectra.